Last week I was asked to have a chat to a friend's teenage daughter, who had her heart set on travelling the world as a fashion model. I've known the now 16-year-old since she was a surprise blue stripe on a stick, and love her like she's my own.

I was aware this time would come, because she has grown into quite a beauty with cream dream skin, copper cascading curls and Jessica Rabbit curves - the latter meaning she has little chance of ever making it on to a catwalk. And despite knowing it would break her heart to hear it, I have never been happier to crush a dream.

You see, I am only too well aware that young girls have a distorted view of the modelling world and the fashion industry it orbits. However, having worked on many glossy magazines throughout my career, I know the reality and wouldn't wish it on anyone. Ever.

And so, I began by telling my teenage friend of my second day working in magazines, the day I had my own heart broken and ideals not so much dashed as bashed.

A casting call for models for a swimwear shoot was taking place, meaning the girls had to sashay past my desk in features to the fashion office behind, where the stylists, editors and photographer were waiting to assess their suitability to fulfil the ''artistic vision'' du jour.

As each model moved by, all white bean lean limbs and Siamese-sharp cheekbones, I was open-mouthed with admiration and awe. Never had I seen girls so stunning, so flawless, so otherworldly exquisite.

Then, I heard the comments from the team as each girl left. ''Did you see her ankles?'' ''She was just awful. Who sent her?'' ''She's what I call a catadog - a girl who wouldn't even make a Best and Less sales catalogue.'' ''Did you see what she was wearing? Was it Katies?'' ''All I know is I hatie.'' ''Fat.'' ''Haggard.'' ''Old.'' Giggles all round.

I don't know what upset me more, the fact I was now working with a bunch of shallow bitches or the humiliation that my new dress to impress on day two in the fashion world actually was from Katies.

I looked down at my own ankles anew and wondered if I, too, was being assessed like fatty cuts of scrag at the butcher's. Suddenly tears emerged and I felt ill. I wanted my old job back. I wanted out of this world. I didn't belong. I never would. And I no longer wanted to.

Within minutes I was in my editor's office explaining I had made a big mistake. I was a writer, not a fashion plate. And here - and I swear this is true (witnesses exist) - was her reply: ''Look, you are not in newspapers now and things are different in fashion. You are a lovely writer but if you want my job one day, I suggest you think about losing 10 kilos [I weighed 64] and investing in some decent clothes. You know, if you did that, had dermabrasion and a nose job, you could be really pretty. Honest!''

My teenage friend interrupted me, clearly only picking up on the bits of the story that appealed. ''Yes, but didn't you become an editor yourself years later, without doing any of those things?'' she said.

It was time for lesson two.

I explained that during my mag years, I was told there are two tests to check out if you have a good body. The first is the pencil test. If you tuck a pencil under your breast and it stays there, you are a fail. If it falls to the ground, your breasts are acceptable.

''I could hold an entire rainbow of Derwents under mine even at your age,'' I admitted, as my young friend looked down at her own ample cleavage for the first time with disdain.

The second is the insidious three-diamond leg test.

This entails you having a diamond shape of space at your ankles, knees and thighs, something I believe is impossible unless you are standing in a food queue in Eritrea. And that is so not chic. It is called dying and desperate.

With this, I got my pretty young friend to give herself these tests then see how she feels about modelling.

While she was unfastening her bra I read out an interview I'd read only that morning with 22-year-old international model Karolin Wolter. ''During my first fashion week in 2009 I was 53-55 kilograms, almost 10 kilograms under my natural body weight,'' she said. ''I did really well but even then my agents were telling me 'You know Karolin ... You have to be even skinnier'. It completely f---ed with my mind.''

Wolter says she is now a healthier ''plus size'' catwalk model. Which means she is size 10-12.

While waiting to hear the sound of a pencil drop that never came, I told my young friend of the models I have seen naked behind fashion shows over the years (catwalk models are different to photographic models - they need to be just coat hangers that move) - how their hips stick out like bony door handles, how you could grate cheese on their collarbones and how many are covered in a downy layer of hair - nature's way of keeping the body warm when it's starved.

I told her how I watched models ingest nothing but black coffee and Marlboros for days on end; how their breath smelt and they would routinely faint.

I recalled models telling me they never feel they are pretty enough; that someone younger, thinner or with a more ''now'' look was always close behind. And how even the handful of genetic freaks that make it to the top still have their so-called imperfections removed with Photoshop.

I reminded her that she would be lucky to get any work past 30, because 25 is considered old in that world. And how drugs are everywhere, not just for fun but to stave off the constant hunger that gnaws at empty, flat bellies. And how constant rejection never gets easier to take.

I was about to go into the pain of bleeding feet from torturous shoes, bone corsets that crush ribs, or the hell of standing in sub-zero temperatures in swimwear while someone yells at you to look sexier - but after discovering she hadn't managed even one diamond (ankle issues), my young friend was no longer listening.

''So, I think I want to be a journalist now,'' she said, hoovering a handful of Pringles. ''Surely that's got to be a better career prospect?''